Markers / Condition
Which genes decide how you handle caffeine and alcohol?
Two of the most reliably personal results in all of consumer genetics, because both involve single enzymes with large, well-measured effects. Alcohol in particular is one of the few places where a genotype changes a health recommendation outright.
The markers
| Marker | Gene | What it does | Evidence |
|---|---|---|---|
| rs762551 | CYP1A2 | How fast you clear caffeine | moderate |
| rs2472297 | between CYP1A1 and CYP1A2 | How much coffee you actually drink | established |
| rs73598374 | ADA | How deeply you sleep | moderate |
| rs671 | ALDH2 | Alcohol flush reaction | established |
| rs1229984 | ADH1B | How fast alcohol becomes acetaldehyde | established |
How fast you clear caffeine
rs762551 · CYP1A2
CYP1A2 does about ninety-five per cent of the work of breaking caffeine down. This position marks the faster and slower versions of the enzyme.
Two copies: Slow metaboliser
How much coffee you actually drink
rs2472297 · between CYP1A1 and CYP1A2
This is not about whether caffeine affects you. It is about how much coffee people with this version end up drinking, which turns out to be one of the most reliably replicated findings in the whole of behavioural genetics. People who clear caffeine faster drink more of it to get the same effect.
Two copies: Typically highest coffee intake
How deeply you sleep
rs73598374 · ADA
Adenosine is the molecule that builds up while you are awake and makes you feel sleepy, and it is what caffeine blocks. This variant slows the enzyme that breaks adenosine down, so sleep pressure builds higher, and carriers show measurably more deep slow-wave sleep.
Two copies: You have the slower enzyme on both copies
Alcohol flush reaction
rs671 · ALDH2
Alcohol becomes acetaldehyde, which ALDH2 then clears. One change disables the enzyme so completely that a single working copy is not enough, and acetaldehyde builds up: flushing, nausea, racing heart.
Two copies: Strong flush reaction expected
How fast alcohol becomes acetaldehyde
rs1229984 · ADH1B
This is the other half of the alcohol story. ALDH2 decides how fast acetaldehyde is cleared; ADH1B decides how fast it is made. The fast version produces acetaldehyde quickly, which makes drinking less pleasant and is strongly protective against alcohol dependence.
Two copies: Two fast copies
Which versions do you carry?
All of these are readable from an ordinary home DNA test file, in your browser, without uploading it anywhere.
Read my fileCommon questions
Which genes decide how you handle caffeine and alcohol?
Two of the most reliably personal results in all of consumer genetics, because both involve single enzymes with large, well-measured effects. Alcohol in particular is one of the few places where a genotype changes a health recommendation outright. The markers most often cited are rs762551 in CYP1A2, rs2472297 in between CYP1A1 and CYP1A2, rs73598374 in ADA, rs671 in ALDH2, rs1229984 in ADH1B.
What does rs762551 do?
CYP1A2 does about ninety-five per cent of the work of breaking caffeine down. This position marks the faster and slower versions of the enzyme. Carrying two copies: slow metaboliser.
What does rs2472297 do?
This is not about whether caffeine affects you. It is about how much coffee people with this version end up drinking, which turns out to be one of the most reliably replicated findings in the whole of behavioural genetics. People who clear caffeine faster drink more of it to get the same effect. Carrying two copies: typically highest coffee intake.
What does rs73598374 do?
Adenosine is the molecule that builds up while you are awake and makes you feel sleepy, and it is what caffeine blocks. This variant slows the enzyme that breaks adenosine down, so sleep pressure builds higher, and carriers show measurably more deep slow-wave sleep. Carrying two copies: you have the slower enzyme on both copies.
What does rs671 do?
Alcohol becomes acetaldehyde, which ALDH2 then clears. One change disables the enzyme so completely that a single working copy is not enough, and acetaldehyde builds up: flushing, nausea, racing heart. Carrying two copies: strong flush reaction expected.
Reference information, not medical advice and not a diagnosis. See the medical disclaimer.